(1) Field of the Invention
The present invention relates to a multi-media information record device and a multi-media information playback device: the multi-media information record device records multi-media information like dynamic/still picture, graphics, sound and the like in a storage device and a recording medium provided to a data server; the multi-media information playback device plays back the multi-media information inputted via a recording medium and a transmission line.
(2) Description of the Related Art
Recently, TV game sets, electronic publications, quality karaoke sets and video on demand devices are used as read-only multi-media information playback devices. These multimedia information playback devices play back multi-media information recorded in a optical disc (CD-ROM) and a digital video disc (DVD), and also multi-media information transmitted from a data server via a network and the like.
The following explanation is about “Denshi Kamishibai-Electronic Picture-Card Show” disclosed in Japanese Laid-open Patent Application No. 5-28648, which is an example of the conventional multi-media information playback device mentioned above. FIG. 1 is an example of a data configuration of multi-media information of a conventional multi-media information playback device, by which images and sound are synchronously played back.
Data and information shown in a data area section and control information section of FIG. 1 are recorded in the recording medium like a digital disc. Control information shown in the control information section is recorded in each block composed of predetermined amount of data shown in the data area section, in which sound data and still picture data mingle. In the data area section of FIG. 1, An (n is a natural number) represents sound data: VnB and VnC represents still pictures A and B, respectively; CLUT (color look up table) represents CLUT data; NOPn represents data to which no operation is applied. In the control information section, (1) represents a data write command; (2) represents a CLUT data command; (3) represents a data display command; (4) represents an audio data command; (5) represents a command of no operation. In the screen image section, A and B represent still pictures A and B, respectively. Both of them are displayed on the screen.
Each command in the control information section is executed in order from the left side to the right side. First, audio data A1, which is digitalized sound information, is transferred to audio data memory by the control information (4), and outputted as an analog audio signal via an audio D/A (digital/analog) converter. Video data V1B is written in a predetermined position of video memory of V42B from V1B, after the write area of a still picture is designated by the control information (1). The CLUT data updates the screen image by the control information (2). Based on a CLUT memory, contents of the video memory are converted to an analog video signal by the video D/A converter, so that the contents are displayed on the screen. While the screen image and an audio signal A44 in FIG. 1 are synchronized, a still picture A can be switched to a still picture B. Although the succeeding still pictures C, D, E . . . are not shown in FIG. 1, the same processing is carried out to play back display screens and sound synchronously.
The next explanation is about a general playback processing of a multi-media information playback device. Multi-media information playback device places a line end signal and a page end signal, which are already inserted in the digitalized image signals, at the end of a scanning line (normally more than 500) and a page (contents of a screen at every 1/30 second) in the display device like Cathode Ray Tube and Liquid Crystal Display, respectively, and displays the scanning lines on the proper pages, so that image signals recorded in the recording medium like a CD-ROM and a DVD are displayed at predetermined positions on the screen of the display device. Multi-media information playback device quadruples a size of an image to be displayed on the screen by using two pixels vertically and horizontally, which forms the smallest square of four pixels, for each pixel in the display device, or by interpolation. This device also reduces an image to a quarter size, by skipping a pixel vertically and horizontally.
Also the multi-media information playback device rotates an image to be displayed on the screen by converting coordinates of each pixel using trigonometric function. As pixels are more dense in the recording medium than in the display device, predetermined adjustment is applied to the recording medium so that a proper image is displayed based on the pixel density of the display device, in time of normal display. So practically, there's no problem when an image which is stored in the CD-ROM as a small still picture is enlarged as much as possible on the screen of the display unit.
Generally, the multi-media information playback device is equipped with necessary programs to play back the multi-media information stored in the recording medium. Sometimes, a different program is already written in the multi-media information so that commands which are added to the multi-media information or which are changed are executed according to the program. In this case, signs which are similar to “[”, and “]” are given to the different program which is described by the multi-media information, so that the multimedia information playback device recognizes the program to be executed.
Moreover, the multi-media information playback device displays a still picture, which does not change at all during the display time, in the display device by repeating the steps of reading and displaying the display data stored in a VRAM (video RAM) every 1/30 second or so. On the other hand, dynamic pictures are displayed by repeating the steps of updating the display data stored in the VRAM, reading and displaying the updated display data every 1/30 second or so. Therefore, one storage unit of page data which shows each screen image of the display device is about 1/30 second for dynamic pictures.
Sound which is played back synchronously with the dynamic pictures can be delimited by 1/30 second or so and stored with each page data which consists the dynamic picture. Therefore, the multi-media information playback device is equipped with a storage unit which stores sound data of at least 1/30 second so that the sound is successively played back along with the dynamic pictures.
As for DVD, details can be found in the next reference; “Movies can be stored in a hard disc; photo-electric magnetic and phase change”, featured in Jul. 18, 1994 issue of “Nikkei Electronics No. 613”, pages 76-81.
However, in the conventional art mentioned above, data about movies, sound, and their controlling, are stored fixedly. Specifically, in the case of image data, data for the whole screen image including the background is stored as one still picture data. Therefore, when part of the screen image is changed by, e.g., moving a part of the still picture to a different position on the screen, enlarging or reducing a part of the still picture, more still picture data coping with the change has to be stored in the CD-ROM or the DVD. So the maximum number of the still pictures which can be displayed is limited by the storage capacity of the CD-ROM and the DVD. Moreover, each time the still picture data is displayed, they have to be read from the CD-ROM and the DVD, so the number of still pictures which can be displayed per unit time is limited by the data transfer rate between the CD-ROM or the DVD and a memory.
When the audio data, the still picture data, the dynamic picture data and the control information are stored in different storage areas, the multi-media information playback device has to access different storage areas of the CD-ROM or the DVD in order to read the control information and each data used for it every time it executes the control information. This results in bad read efficiency. Also, load of the multi-media information playback device for controlling the internal memory is large since data are separately read into the memory provided to the multi-media information playback device from the different storage areas of the CD-ROM and the DVD.